The invention relates to a method of detecting a heat source such as a forest fire in an area to be watched and a system for carrying out this method.
It is known in the art to use for this purpose a detector installed on a tower to carry out a watch through a horizontal and, if necessary, vertical sweeping movement. When using a passive detector that senses the heat source through the infrared radiation emitted by the source, at least two detecting stations geographically remote from each other are required to locate the heat source. This drawback is eliminated when using active detecting stations, for instance of the type that emits a laser beam, locating a heat source by analyzing the portion of the emitted radiation back-scattered by the smoke column produced by the fire to be detected. However, this detecting process suffers from the major drawback that the sweeping movement takes place in a single plane, for example a horizontal plane, that causes those fires that break out in hollows to be difficult to detect or to be detected too late because the smoke column would be dissipated, for example by the wind, before rising up to the sweeping plane.